Mttltioitice telephone system



Nov. 2'), 1923. 1,475,590 T. G. MARTIN ET AL MULTIOFFIGE TELEPHONE SYSTEM Filed March 22, 1920 4 Sheets-Sheet 1 g Q 55: [J is [I] Imam? 7741.507 GMRWN9 BERMRDD MLL/s EFT g:

Nov. 27, 1923. 1,475,590

T. e. MARTIN ET AL MULT I OFFICE TELEPHONE SYSTEM Filed March 22 1920 4 Shoots-Sheet 5 w All.

w I -IZ'LUEHZUPE' 774L507 GMm/vy BER/mwDMLL/s.

Nov. 27, 1923. 1,475,590

T. G. MARTIN ET AL MULTIOF'FI CE- TELEPHONE SYSTEM Filed March 22 1920 4 Sheets-Sheet 4 Patented Nov. 27, 1923.

UNITED STATES PATENT OFFICE.

TALBOT G. MARTIN. OF CHICAGO. AND BERNARD D. WILLIS. OF OAK PAR-K, ILLINOIS,

ASSIGNOBS 'IO AUTOBIATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A COR- PORATION 01E ILLINOIS.

MULTIOIFICE TELEPHONE SYSTEIVI.

Application filed March 22, 1920.

T 0 all whom it may concern:

and BERNARD D. TILLTS. both citizens of the United States of America. and residents of Chicago. Cook County. Illinois. and Cal: Park, Cook County. Illinois. respetively. have invented certain new and useful Improvements in Multiotiice Telephone Systerms, of which the following is a specification.

Our invention relates in general to multi' oflice telephone systems but more particularly to such systems as comprise in one net work offices or exchanges of two different kinds, the offices of one kind being manual offices wherein connections are completed by operators, while the other kind of otiiees are automatic oflices in which connections are completed by means of automatic switches; and the object of the invention is to provide new and improved circuit arrangements for handling inter-office calls between the automatic and manual exchanges.

Systems having both kinds of exchanges as above pointed out are becoming quite common and may arise either by consolidation of existing manual and automatic systems serving the same territory. or by the process of changing over a manual system to an automatic system. Usually in the latter case only one oiiiee at a time is converted from manual to automatic and it Follows that during the period oi transition there will necessarily be both kinds of otfices in operation. However thissituation may arise. it is necessary to provide suitable circuit arraiigements for handling calls from the manual olfices to the automatic otiices, and from the automatic offices to the manual, offices. Our invention is concerned only with the latter class of calls. and provides in general a trunking system comprising automatic to manual trunks which are accessible to selector switches in the automatic otlice and terminate in plugs in Front of a B operator at the manual oliice. together with call registers for registering the digits in telephone numbers called by automatic subscribers when the trunks are taken for use. and an indicating device upon which such numbers are shown to the operator one after the other as fast as she can complete the desired connections.

special object is to provide circuits such Serial No. 367,850.

that automatic subscribers are not required to talk to an operator when engaged in establishing a connection to a manual subscriber. and are not required to perform any other acts which might indicate that the system is not tull automatic. The telephone numbers may all be of the same character and the operations so far as the calling automatic subscriber is concerned. and so far as he is aware of, are identically the same whether he calls a party in an automatic exchange or in a manual exchange. By thus providing for uniform methods of calling by the automatic subscribers the probability of error and confusion in automatic tomanual calls due to the two different types 0t exchanges is entirely eliminated. Other advantages, not now specifically mentioned. will be pointed out during the explanation of the operation of the system which is included in the detailed specification which is to follow. reference being had to the accompanying drawings forming a part thereof. t

In the drawings. comprising Figs. 1, 2. 3. and i. we have shown by means of the usual circuit diagrams the apparatus and circuit connections thereoi which is involved in a complete connection extending from the au tomatic substation A. Fig. 1. to a manual substation A. Fig. 2. The apparatus indicated in Fig. i is located in an automatic exchange. while the apparatus indicated in Figs. 2. 3. and 4 is located in a manual ex change. Inasmuch as the automatic switching equipment itself and the manual equipment are both well known and of the usual type. no detailed description of the inechanical Features of this apparatus will be given, except in so far as it is found convenient or necessary to do so in the explanation of the operation of the circuits.

Referring to F l. the substation A is one oi a plurality of ordinary automatic substations terminating in the automatic exchange previously referred to, and is provided with the usual talking equipment and ringer. and also with a calling device of well known type which is indicated by the reference character 9. through the medium of which the subscriber controls the central oiiicc switches.

The line conductors l1 and 12 extend to the. exchange where they terminate in the line switch C. which may be briefly descril' ed as a rotary line switch whose movable terminals or wipers have no normal position. and which have movement in a Forward direction only. The construction of line switch 0 this type is well known in the art. and its function. also well understood. is to extend its associated line when calling to an idle trunl: line. In carrying out this object. a plurality of these individual, line switches are given access to a group oi trunl: lines extending to first selector s itches. One of the trunk lines to which the line switch C has access is shown n the drawing extending to the first selector D, which is a vertical and rotary selector ot the well known Qtrowger type. In a multi-oflice system of the kind herein contemplated the first selector switches are usually known as otlice selectors and the selector D in common with a plurality of similar selectors has access to a plurality of groups of trunk lines. each of which groups may extend to a different otiice or exchange in the system. Some of these groups of trunk lines may extend to automatic exchanges. while other groups may extend t manual exchanges. A trunk line in one of the latter groups is shown in the drawing. and extends by wayot the repeater E and trunk line conductors 130 and 131, to the plug ending cord circuit O. Fig. 2. The repeater E is an automatic impulse repeater of the general type in common use. and in addition has provisions for repeating operat ing impulses to the distant manual exchan ge. provides holding circuits for the automatic switches in the automatic exchange, and thus renders it unnecessary to use more than two conductors for the inter otlice trunk line. The cord circuit 0 is one of a plurality of similar cord circuits at a P) operators position in the manual exchange and constitutes the means whereby the trunk line shown may be connected by the operator with any one of the manual lines terminating in the manual. exchange. One of these lines is the line of substation A. which terminates in the jack J, shown at the right ot Fig. 2.

From the foregoing it. will he understood that the operation of an o'liice selector. such as the selector D, in response to the calling of the first digit in the telephone number of a line in the manual exchange, will result in extending the connection from the line of the calling automatic subscriber to an idle plug ending cord circuit in the manual eachanoje. In order to take care of theremaining digits in the numbers there is provided for each B operators position a plurality of register sets, each set being capable of registering all the digits in a telephone mum-- her, with the exception. of course, of the first digit which controls the otfice selector shown in the automatic exchange. In Figs.

3 and 4 we have shown one oi" these register sets complete. It comprlses register swi .ch

R Fig. and register switches P R and R Fig. 4. The register switch R is a simple 10 point rotary switch. having the operating magnet 306 and the release in agnot 305. lVipers 307 and 308 have a step by step movement over their associated banks of contacts under control of the operating magnet 306, and are restored to normal position by the release magnet 305. Register switch R responds to the second digit of the called number and after it has operated transfers certain control circuits to register switch R which is thus prepared for operation in response to the third digit. ister switches R R and R are similar in construction to the register switch R and are actuated in response to the calling of the third, fourth, and fifth digits in a called number. respectively.

It will be understood that the number of registerswitches in the register sets may be changed at will toprovide for any desired numbering system. As shown herein the registers R R and R are intended to be controlled responsive to digits which cor respond to the line designation of the called station, while the register R is operated only in case the called station is a party line station. As shown. therefore, provision is made for registering three regular digits and an additional party line or selective ringing digit. In case the numbers to be registered contain tour regular digits an ad ditional register switch similar to register switch B may be inserted between register switches R and R The function of the registers will be pointed out more fully in. the detailed explanation. when it will. he understood fully how the scheme may be changed to provide for any desired numbering scheme.

As before stated there is provided a plurality of register sets for each R operatofis position, and in order to show the relation between the register sets we have shown in Fig. 8, the first register switch of t Ht. 5-} 0nd register set. This register switch is in dicated by reference character P and is exactly like the register switch R The con nections between the different register sets are made at the first register switches in each set. as shown in Fig. 3. and will be explained fully later on.

Each register set is also provided with a. time cont-rolled switch which in the case oi the register set shown in Figs. 3 and l is indicated by the reference character P, Fig. 4;. The switch P is similar in constructioh to the register switches but is operated by the timing mechanism instead of ly means of impulses corresponding to digits in the called telephone numbers. 'The' timing mechanism, which may be common to the exchange. is indicated by the reference character T. and may consist of any suitable kind of clockwork controlled mechanism which is adapted to produce impulses at the rate of two per second.

In order to properly extend calls which are received at the manual exchange to the register sets each cord circuit is provided with an individual rotary line switch. and these line switches have common access to all the register sets. The reference char acter C. Fig. 3. indicates a rotary line switch which is individual to the cord circuit i). Fig. 2. and which has access to the first and second register sets shown. and also to the other register sets which are provided at the B operators position in wh ch the cord circuit 0 terminates. Line switch C is of the same construction as the line switch (I. Fig. 1. although the circuits are modified somewhat in order to take care of the somewhat different requirements.

The indicating device by means of which called telephone numbers are shown to the B operator is shown in Fig. 2. where it is indicated by the reference character V. It comprises essentially a plurality of banks of switchboard lamps. there being one bank of lamps for each register switch in a row ister set. It will be readily understood that the lamps have the function of illuminating the digits in the called mnnbers and cansing them to stand out so as to be readily distinguished. The digits are preferably marked in black on the reverse side of a white semitransparent surface. and ordi narily are not very conspicuous. But when the switchboard lamp immediately behind any character or figure is lighted. such character or figure will stand out very clearly. and is read with great facility. In view of the fact that the connections are extremely simple they have not actually been drawn out. but will be briefly explained as follows: The conductors 351 and ctc.. which terminate in the ten bank contacts associated with the wiper 308 of the first register switch. are connected. respectively. to the lamps 1. 9. etc.. of the first digit group of lamps. The conductors 371. 372. etc.. which come from the ten banlr. contacts associated with wiper 366 of, the register switch R are connected. respectively. with lamps l. 2. etc. of the second digit lamp group. In a similar manner the conductors coming from the banks of the register switches and R are connected to the lamps of the third and fourth digit groups. It should be stated furthermore that each group of lamps is not only connected to bank contacts in a certain register switch of the first set. but is multipled to corresponding register switches in all the other reger sets at the position.

Having delscribecl in a general way the layout of the system herein disclosed the operation of the circuits will now be described more in detail. it being assumed for this purpose that the subscriber at substation A. Fig. 1, desires to obtain a connection with the manual subscriber at substation A. Fig. 9. It will be convrmicnt to assume in the first instance that the station A is a party line station. having the telephone number 23451. as this will afford an opportunity for explaining the operation of the party line register switch ll". Afterward certain modifications having to do with the calling of other numbers will be considered also. hen the receiver is removed at substation A. a circuit is completed over the line conductors 1] and 12 for the line relay 1% of the individual line switch Upon energizing. the line relay completes at its armature a circuit. which extends through the switching relay l3 and the stepping magnet 15 in series to battery. and at its armature 19 connects the test wiper 26 to the above circuit at a point midway between the switching relay and the said stepping magnet. The opcration now depends upon whether the first selector trunk with which the wipers of the line switch are in connection is busy or is not busy. If this trunk line is busy the test contact 31 associated therewith will have a ground potential upon it. the switching relay 1?) will be short circuited. and the stcppine; magnet 15. which interrupts its own circuit. will operate as a buzzer to advance the switch wipers -27, inclusive step by step in search of an idle trunk line. This operation will continue as long as the test wiper 26 continues to engage grounded or busy test contacts, However. we may assume that in the present case when the call is initiated the selector E is idle, and the test contact 31 therefore is not .stl'oundcd, Under these circumstances. when the line relay l-lis energized the switching relay 1? is energized immediately afterwards. with the result that the line conductors ll and L) are disconnected from the winding of the line relay ll. and from ground, respectively. and are extended by way of armatures l6 and 19 and their working contacts. wipers 25 and 27. bank contacts and 32. and armaturcs (i0 nd 12 and their resting contacts. to the upper and lower windings of the line relay of the selector l). i

As soon as the line is (XiGlH'lCtl to the selector D as above described. the line relay 50 will be @llGl'QlZltl and will close the circuit of the slow acting release relay 51. Upon energizing". the latter relay prepares the circuits of the selector for operation in its vertical movement in the usual manner. and also completes a holdine: circuit extending back to the line switch C as follows: ground at G working contact of armature 63 and the said armature, conductor 64, bank contact 31, test wiper 26, armature 17 and its working contact, winding of the switching relay 13. and the winding oi the stepping magnet 15 to battery. It is understood that the above holding circut is completed before the slow acting relay 14: has had time to deenergize. In addition to maintaining the switching relay energized, the holding circuit also serves to provide ground to the multiples of test contact 31 and also to the multiple test contacts in which the private normal conductor 28 terminates in the banks of the connectors which have access to the line of substation A, thereby guarding the connection against intrusion in the customary manner.

The calling subscriber may now operate his calling device S in accordance with the first digit of the desired number' Two interruptions are thereby produced in the circult of the line relay 50, and the said line relay is accordingly twice deenergized moi'nentarily, transmitting at each deenergization an impulse of current through the slow acting series relay 52 and the vertical magnet to battery. By the operation of the vertical magnet the selector shaft is raised two steps, whereupon the wipers 7072, inclusive. will be standing opposite the level of. bank contacts in which are terminated the trunk lines extending to the manual exchange. The slow acting relay 52 is energized in series with the vertical magnet, retaining its armature attracted throughout the vertical movement of the switch, and upon the closure of the vertical otl normal springs 59 completes a circuit for the stepping relay 53. Upon energizing, relay 53 prepares a circuit for the rotary magnet 54; at its lower armature, and at its upper armature establishes a locking circuit for itself. At the end of the vertical movement of the switch the slow acting relay 52 is deenergized and closes the circuit of the rotary magnet, which is thereupon energized to advance the wipers 7072, inclusive. into engagen'ient with the first set of banlr contacts in the level opposite which they were raised. The rotary magnet 5% also breaks the locking circuit of the stepping relay which accordingly is deenergized and breaks the circuit of the rotary magnet, which thereupon deenergizes also and a gain closes its interrupter contact. The operation now depends upon. whether the trunk linev with which the wipers have connected is busy or is not busy. If this trunk line is busy the test contact associated therewith will be grounded and the stepping relay 53 will be energized over a circuit which extends by way of the test wiper 71, armature 61 and its resting contact, interrupter contact of the rotary magnet, off normal springs 59, and the winding of the steptest ontact 74: and the rotary magnet is deenergized, the stepping relay 58 w11l not .i relay which heretotore has been shortcircuited, will be energized by current flow.- ingover the following path: grounded conductor 642:, rinding of the switching relay 55, interrupter contact of the rotary magnet 5 1, oil normal springs 59, and the winding of the stepping relay 53 to battery. Owing to the high resistance of the switching relay 55, stepping relay 53 is not operated. Upon energizing, relay disconnects the incoming line conductors from the windings oi the line relay 50 and extends them by way oi": armatures 60 and 62 and their working contacts, wipers T0 and 72, and normally closed contacts of the reversing relay 100 to he upper and lower windings of the line relay 101 of the repeater E.

ll hen the line'is extended to the repeater as above explained the line relay 101 is energized and closes a circuit of the slow acting release relay 102. Upon energizing, relay 102 completes a holding circuit extended back to the selector D and line switch C as follows: ground at G armature 112 and its working contact. conductor 77, test contact 'Z l, test wiper 71. and the armature 61 and its working contact to conductor 64, where it joins the previouslydescribed holding circuit xtending back to the line switch The above described circuit serves to maintain relays 55 and 13 energized throughout the duration of the connection.

In addition to closing the holding circuit for the automatic switches C and D, the relay 102 of the repeater E prepares a circuit at its armature 115 for the slow acting relay 103, closes a circuit at its armature 114 which energ zes the polarizing winding of the electro-polarized relay 1.05, and at its armature- 113 completes a bridge across the trunk conductors 130 and 131 which may be traced over the following;- path: conductor 130. armature 113 and its working contact, armature 116 and its resting contact, upper winding of the electro-polarized relay 105, normally closed contact springs controlled by armature 107 of relay 100, right hand winding of the impedance coil 106, and armature lltand its working contact to the n be operated, but instead the switching Ill conductor 131. By the closure of this bridge across the trunk line a circuit is completed for the double wound line relay 203 in the cord circuit 0, and the said relay 203 is therefore operated. Upon energizing, relay :1 completes parallel energizing circuits for the slow acting relays'2'l0 and 202. These relays are theretore energized at the same time and may be considered as one relay, but in 'view oi the large number of contact springs it is advisable in practice to use two relays with the contact springs divided between them. Relay 201 prepares a circuit for the reyersing relay 204 at its armature 210, at its armature 216 connects direct ground to the lower winding of the line relay 203, and at its armature 229 prepares a circuit for the call signal lamp L Relay 202 at its armature 217 prepares an operating circuit for the register switches of whichever set is later selected, and at its armature 218 closes an operating circuit for the individual line switch 0 which extends as tollows: ground at G*, resting contact 0? armature 215 and the said armature, work ing contact of armature 218 and thesaid armature. conductor 242, armature 256 and its resting contact, common conductor 151, and armature 156 and its resting contact to battery. Upon the completion of the above circuit the line relay 251 is energized and at its armature S closes a circuit for the switching rela 250 in series with the stepping magnet At the same time, at its armature 257, the line relay connects the test wiper 262 with the above mentioned circuit at a point midway between the switching relay and the said stepping magnet, whereupon a trunk selecting operation will take place similar to that which has already been described in the case of the individual line switch C. For the sake of simplicity it will be assumed that the Wipers of the line switch (7 are already in connection with the bank contact set associated with the first register set. as shown in the drawing. and it will be assumed furthermore that this register setis idle. It will be evident therefore that test contact 266 will not, be grounded, and no rotation of the: line switch C will take place. The switching relay 250 is at once energized and establishes a locking circuit tor itself at its armature 255. Relay also performs a number of other circuit changes which may be mentioned briefly as tollows; At armature 25a ground is connected to the test wiper 262 for the purpose of rendering the multiples of test conta t 260 busy in the banks of the other rotary line switches, at a-rmatures 253 and 269 conductors 243 and 2 11 are extendedthrough to wipers 260 and 263, respectively, and at armature 256 the conductor 242 is disconnected from the winding of the line relay 251 and is extended by way of the working contact of armature 256, wiper 261, bank contact 205, and the winding of relay 300 of the register switch R to battery. Upon the closure of the circuit relay 300 is operated and at its armature 309 disconnects ground from the common conductor etc, at its armature 311 disconnects ground from a releasing circuit extending over conductor 330 which will be described later on, and at armature 310 closes an operating or control circuit tor the register switch R which will shortly be traced in full.

The apparatus is now ready for the reception of the series of impulses corresponding to the first digit in the local number of the called line in the manual exchange. It is understood, of course, that the first digit in the telephone number which operated the selector D at the automatic exchange has to do with the office selection only and does not appear in the multiple at the B operators position. When the dial of the calling device S is operated in accordance with the next digit therefor another series of interruptions, three in this case, will be produced in the line circuit and will bring about a like series of deenergizations the line relay 101 of the repeater E.- At each deenergization relay 101 at its armature 110 sends an impulse of current to the slow act- Eng relay 103 which is energized at the first impulse and maintains its armature attracted while the repeater is repeating a series of impulses. In its energized position relay 103 completes a bridge across trunk conductors 130 and 1231 over adirect path which may be traced by way otarmature 113 and its working contact, armature 116 and its working contact, and armature 111 and its working contact to conductor 131. At the same time that the line relay sends impulses to the slow acting relay 103, it also produces a series of interruptions in the bridge across the trunk conductors 130 and 131 by means of its armature 111. These interruptions cause the line relay 203 in the cord circuit 0 to be deenergized a plurality of times, and at each deenergization the said relay transmits an impulse of current to the steppingmagnet 300 o'l' the register switch R over the following path: ground at G, armature 221 and its restng contact, w0rking contact of armature 217 and the said armature, conductor 2&3, armature 253 and its working contact, wiper 200, hank contact 264, armature 310 and its working contact, normally closed contact springs controlled by armature 312. winding of the slow acting relay 302. and thewinding oi the stepping magnet 300 to battery. Since three interruptions are produced by the calling de vice S, which were repeated as above described. the stepping magnet 306 will receive three impulses of current and the wipare 307 and 308 will be rotated three steps Lil and will come to rest in engagement with the third contacts in their respective banks. The operation of wiper 308 produce no result at this time, but Wiper 307 when it moves out of normal position closes a circuit for the relay 301 which upon energizing changes the operating circuit so that it extends by way of the armature 310 and its working contact, working contact of armature 312 and the said armature, armature 315 and its working contact (slow acting relay 302 being now energized), winding of relay 302 and the winding of the stepping magnet 306 to battery. Relay 301 also prepares a circuit for the release magnet 305 at armature 313, and at armature 314 connects ground to test contact 266 and its multiples in the banks of the other individual line switches. The latter operation is for the purpose ott maintain'ng these test contacts grounded during the releasing operation in the register set, as will be pointed out more fully hereafter. The slow acting relay 302, which is energized in series with stepping magnet 306 and which remains in operated position while operating impulses being received, deenergizes after the operation of the register switch R is completed and at its armature 315 extends the operating circuit to the next register switch R as follows: armature 315 and its restingcontact, conductor 329, contact springs controlled by armature 368. winding of the slow acting relay 361, and the winding of the stepping magnet 364 to battery.

The apparatus is now ready to receive the next series of impulses. When the calling device is operated again, this time in accordance with the digit 4, a series of four interruptions is produced in the circuit of the line relay 101 of the repeater E, which are repeated as before with the result that four impulses of current are transmitted to the stepping magnet 364 of register switch R In response to these impulse the stepping magnet 364 is operated to rotate the wipers 365 and 366 four steps, and the wipers are brought to rest in engagen'ient with the fourth contacts in their respective banks. hen the wiper 36' leaves its normal position a circuit is completed for relay 360 which, upon energizing, prepares circuit for the release magnet at its armature 367 and at its armature 368 prepares the operating circuit for transfer the next register switch by the slow acting relay 361. This latter relay is energized in series with the stepping magnet 364 while the said magnet is being operated and de energizes at the end of the rotary movement as was described in the case of the slow acting relay 302 of register switch R The slow acting relay 361 having deenergized, the operating circuit is extended to the register switch R as follows: conductor switch R 329, working contact of armature 368 and the said armature, armature 369 and its resting contact, conductor 329 contact springs controlled by armature 387, winding of the slow acting relay 381, and the winding of the stepping magnet 384 to battery.

The next digit to be called is the last di it which is included in the line designation of the line of substation A which appears in the multiple at the B operators position, the final digit being a party line digit having to do with the selective ringing, as before stated. The calling subscriber may now call the digit 5 with the result that five operating impulses are transmitted to.

the stepping magnet 384 of the register switch R By the operation of the stepping magnet 384, wipers 397 and 398 are rotated step by step until they come to rest in engagement with the fourth contacts in their respective banks. WVhen the wiper 397 eaves its normal position a circuit is com ileted for the relay 380 which, upon enerizing, changes the operating circuit at its rmature 387, the same as was done in the ase of the two register switche previously perated, prepares a circuit for the release magnet 383 at its armature 386, and at its armature 385 prepares a circuit for the timing switch P. The slow acting relay 381 is energized in series with the stepping magnet 384, remaining in operated position while impulses are being received, and at the end of the operation of the register switch R is deenergized, whereby the op erating circuit is transferred to the register as follows: conductor 329, work- 1 contact of armature 387 and the said armature, armature 388 and its resting contact, conductor 329", contact springs controlled. by armature 408, winding of the slow acting relay 401, and the stepping magnet 404 of the register switch It to battery. Register switch R is now ready for ope ation in response to the calling of the party line selecting digit.

lVhen the slow acting relay 381 deenergizes at the end of the operation of the register switch B it closes at its armature 38?) circuit for the stepping magnet 433 of the timing switch P as follows: grounded conductor 399, working contact of armature and the said armature, armature 389 and its resting contact, armature 410 and its resting contact, armature 436 and its resting contart, and the winding of the stepping magnet 433 to the common conductor 435. Since the common conductor 435 is connected to battery at half second intervals by the time mechanism T. the stepping magnet 433 immediately begins opcrating to advance the wipers 437 and 438 step by step over their associated banks oi contacts. As soon as wiper 437 leaves its normal position it completes a circuit for the relay 430 Which upon energizing prepares a circuit for the release magnet 4:32.

The calling subscriber may now operate his calling device in accordance with the digit 1 which is the last digit to be called. By this operation a single impulse of current is transmitted through the stepping magnet 4.0% of the register switch it ore a circuit previously traced and the said magnet is operated to advance the wipers it? and H8 into engagement with the first contacts in their respective banks. When the wiper n7 leaves its nor al position a circuit is completed tor relay 402 which upon energizing prepares a circuit for release magnet 403 at its armature 406, changes the operating circuit in the usual manner at its armature 408, prepares a circuit at its armature 109 which is closed later by armature 401' of relay am and which will be described hereinafter. and at its armature 4x10 breaks the circuitot the stepping magnet L33 oi? the timing switch P. By the latter operation the movement oi the timing switch is stopped, and it may be mentioned here that its operation in the presentcase, where the party line substation A is being called. is of no utility. The function of this switch will be pointed out later on. The slow acting relay 4-01 energized in series with the stepping magnet 40 i ot the register switch R" and when it decnergizes at the end t the rotary movement of said switch a circuit is closed at its armature it)? which extends as follows: grounded conductor H9, working contact o't armature 409 and the said armature, armature 407 and its resting contact, conductor 323, and the winding of the relay 303 to battery. A branch of the above circuit may also be traced by way of conductor 341 to the register set pilot lamp L at the open ators posit-ion. lVhen the above traced circuit is completed the pilot lamp L is illuminated to indicate that the register set associated therewith has a connection set up on it. and the relay 303 is energized. Upon energizing, relay 303 connects the exchange battery by way of resistance 4-70 to the upper terminal ot relay 530i at armature 31.7, and at its armature 316 connects the common conductor 3 H) to the circuit ot relay 30% at a point between the winding of the relay and the said resistance 4170. Assuming now thatthere is no other call switched through onto the indicating lamps relay 304i will be energized over the following circuit: ground at G resting contact of armature L72 and the said armature, conductor 32].. relay 304:. working contact of armature 317 and the said arn'iature. and the resistance lit) to battery. Upon energizing. relay SO-t connects ground to the common conductor 340 by means of armature 318, and at its armatures 319 and 320 disconnects ground G from the loop circuit extending by way winding of of conductor 322 to the No. 2 register set. Two armatures are used in order to reduce the possibility of trouble from a dirty con nection in this circuit.

Relay 304 is the relay which switches over the registered call to the indicating lamps, and the manner in which this done will now be explained. it being recolle-ted that the wipers 0t register sets E F, inclusive, are now resting upon the third, tourth. litth and first contacts in their respective banks. hen the armature 319 of relay 30 i is attracted ground is connected by way of conductor 3418, the common conducting strip in the bank of register switch R with which this conductor is connected, and the wiper 308 to the conductor 353, which it is understood extends to the lamp #3 in the first group of the indicating device V. armature 320 of relay 30 i is attracted ground G is connected to the conductor 32? thereby causing relays 362, 382, and 400 of the other three register switches to he energized. Each of these relays has the t'unction o1 grounding a common strip in the bank lVhen of its associated switch, as shown in the drawing, and it will be clear therefore that when these relays are energized, the wipers being operated as previously stated. conductors 37%, 395, and 411 will be grounded.

These last three conductors extend to the #-'t lamp of the second group, the 5;:5 lamp of the third group. and the B lamp (black) of the fourth group. 'ihe other side of all the lamps is connected to battery as shown in the drawing, and the lamps mentioned are and the said armature, conductor 2-H, resting contact of armature 212 and the said armature, working contact of armature 229 and the said armature. and the lamp L to battery. The lamp L which is indii 'idual to the cord circuit 0, is therefore lighted sinniltaneously with the lamps in the inclicating device V and enables the operator to know which one oi her cord circuits is being used by the automatic subscriber whose wanted number is at this particular time being shown on the indicating device. Haw ing observed the number 345 black, and knowing by the lighting of the lamp If that the cord circuit 0 is the one in use. the opcrator will test the multiple jack of line with the tip of the plug in the usual manner to ascertain whether or not the line is busy.

In case the line is busy the plug will be inserted in a busy ack of well known form and function, in order to give the calling subscriber a busy signal. The busy machine associated with the busy jacks at the B board is preferably 01" the same type and giving the same kind of a busy signal as the busy machine in the automatic exchange, so that the calling subscribers will get unitorrn busy signals in all cases. Assuming however, that the line oi substation A. is found to be idle, then the operator will press the blaclr ringing button, indicated by reference char actor 13 in the drawing, and will insert the plug ot cord circuit in the multiple jacl: #345, this being the jack J in which is terminated the line of substation A. .lt may be mentioned at this time that each cord circuit is provided with the usual black, white, green and red selective ringing buttons as shown, which correspond to the 16, 33, 50, and 66 cycle ringing current frequencies, respectively. The ringing keys are of the self locking type and when any key is epres ed it remains locked in depressed position until another key is operated. l i hen the plu g is inserted in the acl: Ql a circuit completed for the relay 208 in the cord circuit 0 as tollows: ground at G", winding of the cut oil relay 230, sleeve of the aclz l, sleeve oi the plug, and winding of relay 203 to the junc tion point 231, where the circuitdivides, one branch extending by way of the supervisory lamp L to battery, and the other branch or; tending by way of armature 220 and its working contact, working contact of ar1na ture 228 and the said armature (closed as soon as relay 208 energizes), armature 225 and its resting contact. contact springs con trolled by armature 226, and the winding of relay 205 to battery. By current flow over the above circuit, relays 230 and 208 are en ergized in series. the former relay being effective to clear the line of substation A of its normal battery and ground connections, and the relay 208 being effective to disconnect the operators telephone set and close the upper talking strand of the cord circuit at armature 227. The lamp L is lighted when the circuit is first closed by the insertion of the plug, but as soon as the branch circuit through relay 205 is closed by the energization of relay 208 the lamp is extinguished by the shunting of the current through this relay, which is of relatively low resistance. Relay 5505 is the i niging relay, and is energized at this time to close at its armatures 223 and 2- 4- the usual automatic ringing or signalling circuit which, since the black ringing key has been depressed, will include the 16 cycle generator. The ringer at substation A is tuned to the 16 cycle frequency and responds to signal the called subscriber.

The required connection has now been established and he desired party is being signailed automatically in the usual way. Before proceeding with the operations which take place when the called subscriber answers it will be well to consider the release of the register switches which takes place as soon as the connection is established by the insertion of: the plug in the jack oi? the called line. then the plug of cord circuit 0 is inserted in jack J a branch path may be traced from the sleeve of the plug by way of conductor 232 and the winding ot relay 200 to battery. Relay 200 is therefore energized in parallel with relay 208 when the plug is inserted in the jack and upon attracting its armature 212 extinguishes the call signal lamp L Relay 200 also opens at its armature 213 the inductive path which extends from trunk conductor 130 by way of the condenser to conductor 243, shifts its armature 214; from ground to battery for a pur pose which will be explained hereinafter, and at its armature 215 opens the holding circuits of relays 250 and 300 or": the indivnal line switch C and the register switch R respectively. Upon deenergizing, relay 250 disconnects the wipers of the line switch C and the switch is thus restored to normal condition. Nhen relay 300 deenergizes ground G is connected to conductor 330 with the result that the previously prepared cir cuits for the release magnets 305, 363, 383, 41-03 and 4:32 of register switches R R R 1%, and timing switch P, respectively, are com pleted and the said switches are restored to normal. position. lVhen the switches riach normal position relays 301, 360, 380, 402, and 430 are deenergized and the release magnet circuits of the several switches are broken. Relay 301 also disconnects ground from the test contact 266 and its multiples; thereby rendering the No. 1 register set accessible to other calls. VVhe-n the register switches are released as above explained, relays 303 and 30 are deenergized, but the effect of the deenergization of these relays upon other register sets which may be in use at the time will be deferred until later.

Returning now to the established connection, while the called subscriber is being signalled automatically as before explained, the calling subscriber in the automatic exchange is given the well known ringing current induction by means of the circuit through the high resistance 233 which bridges the open contact in the upper strand of the cord circuit at armature 223 of the ringing relay 205. This resistance permits suflicient ringing current to leak back in the direction of the calling subscriber to give an audible signal each time ringing current is applied to the called line, and he is thereby advised that the ringing operation is proceeding. This so called ringing current induction is standard practice in automatic systems and by providing for the same thing in the B operators cord circuits we pro vide for unitorni operating conditions. To proceed. the ring cut oil rela 2 6 included in the ringing circuit. but does not energize as long as the receiver at substation A ren'iains on the hook. W lien the called subscriber at substation A removes his receiver responsive to the ringing of his bell the relay 206 is energized by the increased current flow and opens the back contact of its armature 2135. thereby including relay 207 in the circuit ot the relay 205. Relay 207 therefore is at once energized and upon attracting its armature 226 short circuits relay 205 and locks itself in the. circuit over the sleeve of the cord. In other words, relay 207 is substituted for relay 205., and it may be mentioned that relay 20? is of the same resistance as relay 205 and the supervisory lamp L therefore remains shunted out. iVhen relay 205 deenergizes the ringing circuit is broken and the upper and lower talking strands ot the cord circuit are connected. whereupon the talking circuit will have been completely established. The calling subscriber is supplied with talking battery through the windings ot line relay 101 at the repeater E, and the called subscriber is supplied with talking battery through the right hand windings ot' the re peating coil at the cord circuit 0. Relay 209 is included in the latter circuit and is operated by current flow through the transmitter at substation A to attract its arinature 222 and close the circuitot the reversing relay 204. By the operation. of? the reversing relay 204; the trunk conductors 130 and 131 are reversed as regards their connections with the windings of the line relay 203 and the direction 0t current flow over the conductors of the trunk line is therefore reversed. The direction of current flow through the upper winding of the electropolarized relay 105 at tle repeater E is therefore reversed and this relay is now operated. At armatures 11S and 120 relay 105 closes the bridge over a path which is independent of the contacts controlled by row lays 103 and 101 so that the elements normally in the bridge cannot be cut out or the bridge opened. by accidental operation of the dial at substation A. In addition. at armature 119, relay 105 closes a circuit for the reversing relay 100 in the repeater, which operates in the same way as "as described in the case of the reversing relay 20 1 to reverse the direction of current flow in the line of substation A. This operation may be used for operating a meter or supervisory apparatus and is provided for according to standard practice, although it is of no utility in the particular circuit shown.

operating its armature 107 relay 100 introduces the left hand winding of the impedance coil 106 in the bridge across trunk conductors 130 and 1311 in series with the right hand winding of this coil, thereby increasing the impedance of the bridge and increasing the'efliciency ot the talking circuit.

The required connection having been established. the subscribers may now converse as desired. Then the conversation is finished both subscribers will hang up their re ceivers. Then the receiver is replaced at substation A the circuit of the line relay 101 of the repeater E is broken and relays 110i and 102 are therctore deencrgized. The lat ter relay breaks the holding circuit extending back to the line switch C and the selector D by retractingits armature 112. and as a result relays 13 and 55 are deenergized. Be lay 13 in the line switch C disconnects the wipers of the line switch which is thereby restored to normal condition ready for use in another call. Relay 55 closes the circuit of the release magnet 57 at its lower arniature and the operation of the said magnet restores the selector D to normal position in the usual manner, the circuit of the release magnet being broken by the off normal springs when the switch is completely restored. lVhen the relay 102 of the repeater deenergizes it also opens at its armature 11?) the bridge across the trunk conductors 130 and 131. and thereby causes the line relay 203 at the cord circuit 0 to deenergize. resnlting in the deenergization of slow actin relays 201 and 202 also. Relay 202 by retracting its armature 220 opens the shunt path around the supervisory lamp L which extends through the relay 20.7 to liiattery. and thereby causes the lamp L to be lighted to give the operator a. disconnect signal. Relay 201, upon deenergizing, permits the contact springs controlled by its armature 216 to close. thereby connecting the lower winding of the line relay 203 by .vay of re sistance 234; to battery instead. of ground to which it was formerly connected. By this operation a circuit is established for relay 104 at the repeater which extends as follows: grounded armature 110 of line relay 101, resting contact of the said armature, armature 115 and its resting contact, winding of relay 104:, conductor 131. lower left hand winding of the repeating coil, contact springs controlled by the lower armature of reversing relay 20 1 (this relay being now deenergized), lower winding of line relay 203, normally closed contact springs controlled by arinature 216, armature 214 and its working contact. and the resistance 23% to battery. The relay 10st at the repeaterE is energized by current flow over the above circuit and upon attracting its armature 117 again connects ground to the conductor 77.

By this operation the test contact 4 4 and its multiples in the banks or" the other office lectors are again grounded and the trunk line is made busy.

The automatic switches have now bee released, a disconnect signal has been given to the operator, and the trunk line in. use has been made busy pending; the pulling down of the connection, at the ll board. lVhen the operator observes the lighted supervisory lamp if she will. remove the plug oi. cord circuit (1 trom the jack and relays 230 and 208 will be 0 l, and the lamp L will be eX i. relay 200 will be deeneii'ggizea and ground will again be connected to the lower winding of the line relay 203. as is the normal condition. Relay 10-1 at the repeater therefore deenergrizcd and ground is discon nected from conductor '77. with the result that the trunk line is restored to idle condition. The apparatus he now all been completely returned to normal in madiness for use in other connections.

Having; described the operation ot the set as a whole we will now eiq'ilain certain dctails which it was not conrenieat to go into fully before; and the thii g which will be considered is the function oi? the timing switch P, 4t. The necessity oi? proridinn one of these switches ror each register set is occasioned by the fact that the system herein. contemplated includes both party lines and straight lines. the pa ty lines having one more digit in their telephone numbers than do the private or straight lines. It is understood that means must be provided in each register set for switching over onto the indicating lamps as soon as the registering; ot' a telephone number is con pleted. The registering: oia telephone numher is completed wish the final digit is called, and in the case of party line numbers which have a matinuim numb-er o digits, the problem is a simple one it being; only necessary to provide mean bc last regis ter switcln register sw tor example, for closing the circuit of the relay which in Fm;

places the register set in condition to be switched over. This relay is the in register set No. l. and it has fill; explained fully how the circuit or this re lay is closed as soon as the rep istcr switch. R has finished operating. But when a private line is beino; called the proposition is not so simple. The telephone nun'iher or": a line of this kind will have one less di it than do the party line telephone numbers and when the number is registered therefor the register switch R will never be op rated. it will not do ordinarily to have the register switch R close the circuit of relay 303 directly. because in a party line number is called instead of a private line number this relay would be operated preu'iaturely,

In order to take care of this diihculty we provide the timing switch P. which is started operating as soon as the register switch R has finished its operatioin as previously explained and which after a certain definite time interval closes the circuit of the relay 303. This time interval is calculated in accordance with the average length of time required to call the final digit in a telephone number, and may be of about four seconds duration, or less. To explain the operation a little more fully let it be assumed that some telephone number is being registered and that the register switch R has just com-- pleted its operation. The timing switch P will now be set in motion by the closure ot the circuit of its stepping magnet in a manner which was already described, and will advance its wipers step by step over their associated bank contacts. If the numher being called is a party line number the calling subscriber will immediately call the final digit in the telephone number, which is registered on the register switch li and the operation of the timing switch P will be stopped as soon as relay e02 energizes the circuit of stepping magnet 438 being opened at armature 410. Suppose now that a private line number is being registered, in which case the digit which operates rag ister switch R will be the final digit. The timing switch continues its operation in such case without interference and after an interval of four seconds the wiper 41-38 will place a ground on conductor 439. The circuit of relay 431 is thereby closed, which relay operates to open the circuit of the step ping magnet 4-33 at its armature 436. At the same time a circuit is completed for relay 303 as follows: grounded conductor 439, resting contact of? armature M2 and the said armature restingcontact of armature 409 and the said armature, armature 407 and its resting: contact, conductor 32S. and the wind ing of relay 303 to battery. By the closure of the above circuit relay 303 is energized and in case the indicating amps are not in use relay 304 will be energized also to switch the call over onto the lamps. The operations from now on are the same as have been previously described.

An alternative method of switching on which may be employed at the option of the l5 operator during day time busy periods will now be briefly explained. At such times the number of calls for party line stations is at a minimum because as a general rule all the business houses will have in dividual private lines; and it is found that the service may be speeded up greatly without causing any particular trouble by cutting out the timing switches, which it is undcrstood are provided solely for the benefitof those parties who are calling party line numbers. In order to accomplish this the B operator will operate key K which places a ground potential upon conductor 332 and operates the relay iii-1. "There is a similar relay operated over the same conductor for each ot the other register sets at the position. Relay 441 being in operatedposition, let it be assumed that a call is received and is registered on the No. l register set. As soon as the register switch R finishes its operation a circuit for relay 303 is completed as follows: grounded conductor 399, working contact of armature 385 and the said armature. armature 339 and its resting contact, armature L10 and its resting contact, working contact of armature i 12 and the said armature, resting contact of armature 409 and the said armature, armature 4:07 and its resting contact. conductor 32S, and the wind ing of relay 303 to battery. Relay 303 is therefore energized as soon as the register switch R completes its operation, and the call may be switched over immediately with out waitingfor another digit to be called, or for the time mechanism to operate. Should it happen that a party line number is being called,'no particular harm is done by the switching over onto the indicator lai'nps, should this have taken place. The calling subscriber will generally start to call the final digit bet'ore the'operator has had time to insert the plug into the supposed number of the called line, or perhaps even before she has fixed the number in her mind, and as soon as the register switch R starts operating the circuit of relay 303 will be broken (at armature 407 of relay 401) and the lamps will be extinguished. If another call is waiting it will be switched onto the lamps at once, while if no call is Waiting the call under consideration will be again switched onto the lamps as soon as the register switch R has been operated. Since the lamps ordinarily are extinguished only when the plug is inserted in the jack of the called line, if the lamps go out automatically before she has plugged in, the operator will know that another digit is being called and that she will have to wait for the complete number to be flashed on before she can handle the connection.

lVe will now describe briefly the consecution control circuit connected between the register sets at the same position which controls the switching of registered calls over onto the indicator lamps one at a time. We will suppose that a call has been received and registered on the No. 1 register set, and that simultaneously. or at least before the operator has completed the connection called for by the number registered on the No. 1 set, calls are received on register sets 2, 3, and 1, the relays in such sets which correspond to relay 303 of the No. .1 set being energized and the corresponding pilot lamps being lighted in front of the operator Since all the relays such as relay 303, etc., are energiyed. each of the relays such as relay 304; will have its upper terminal connected through a. resistance to the exchange battery. but none of these relays will be energized at this time because thevc-ircuit extending to ground is opened atarmatures 319 and 320 of the relay 304 of the No. 1 register set. The calls received on register sets Nos. 2. 3. and at, are not switched over at once therefore. but are held up while the operator is establishing the connection registered on the register set No. 1. \Vhen this connection is established by the insertion of the plug in the jack of the called station, the No. 1 set is restored to normal and relays 303 and 30-]: are deenergized. As a result, ground is removed from the common conductor 3&0 and an instant later conductor 321 is connected with conductor 322. As soon as the latter operation takes place ground G is again extended over a series circuit to all the relays such as relay 304C in the three register sets in use, and these relays will startto operate simultaneously. Relay 304', however, is the only relay which completely operates, for this relay disconnects conductor 322 from conductor 323 which extends to the corresponding relay of the next register set, it being understood that the series circuit continues through all the register sets in the same way as is shown in the case of register sets Nos. 1 and 2. Upon energizing,

relay 304 grounds the common conductor 340, and also grounds conductors 348 and 327, by which 'latter operations the registered call is switched over onto the lamps. Suppose now that the register set No. 1 is again taken foruse before the operator has coi'npleted the connection corresponding to the number registered on the No. 2 register set. .As soon as the last register switch of the No. 1 set is operated relay 303 will energize, but now since the No. 2 register set is operatively connected with the indicator lamps the relay 30-l of register set No. 1 will not energize .to switch on the registered call. This result is obtained notwithstanding the fact that now the circuit of relay 304 to ground G is uninterrupted, for since the common conductor 340 is grounded relay 304 will be short cirouited and will not be energized. sponding to the number registered on the No. 2 set has been completed by the operator, the NO. 2 register set is released, relays 303' and 301- are deenergized, and among other operations: which take place ground is removed from the common conductor 340. As soon as this conductor is freed from ground, relay 304 of the No. 1 register set will operate with the-results already described and understood.

It will be seen fromthe foregoing that by means of two circuits, towit, the circuit As soon as the connection corre of the common conductor 340 and the series circuit including conductors 321, 322, 323, etc, provision is made for switching registered calls over onto the indicator lamps one at a time. It will be seen that calls received on the No. 1 register setwill have the preference over calls received on the other register sets: because relay 304.- precedes relay 304 and other similar relays in the series circuit. For the same reason calls received on the No. 2 register set will have the preference over calls received on register sets Nos. 3, 4:, 5, and 6. This is illustrated in the opera tions described in the preceding paragraph in which calls were left standing on the third and fourth register sets while a subsequent call received on the No. 1 register set was switched over ahead of them. This discrimination in favor of the lower numbered register sets is perhaps objectionable, but ordinarily does not cause any trouble because the operator is generally able to complete connections as fast as they are received. It may be stated that in this system the connections can be set up with great rapidity, the operator being able to work with both hands and plug up connections as fast as she can read the numbers which are flashed out by the indicating lamps. It may happen, however, that during extremely busy periods a call in ay be tied up on some register set for an unduly long period. To permit the operator to handle such calls at once we provide a special cut in key' for each register set except the No. 1 register set. These keys are indicated by reference characters K K inclusive, and are located just below the associated pilotlamps. If the operator observes that a call on register set No. 3, for example, has been held up for sometime by a continuous succession of calls on register sets Nos. 1. and 2, she will actuate key K By this operation the relay 471 is energized and ground (ir is disconnected from the series circuit. At the same time, ground is connected to conductor 3J3 direct by means of the key and as soon as the connection being handled is completed the call on register set No. 3 will be switched over to the exclusion of calls which may be waiting on register sets Nos. 1 and 2 which ordinarily would precede the call on register set No. 8.

There is one other condition which may be discussed before concluding. This is the case where a call is received at the operators position when all the register sets are busy. The "common conductor 4:50 is normally grounded at each of the register sets, the

ground connection being shown in the case of the N0. 1 register set at the resting contact of armature 309 of relay 300, and at the corresponding armature in the case of the No. 2 register set. If all register sets are busy it will. be evident that all. of these ground connections in the different register sets will be opened and the common conductor 450 will be clear of ground. The normally short circuited relay 453 is thereupon energized and closes a circuit for relay 455. Upon energizing, relay 455 lights the lamps L to indicate the condition of all register sets busy, and at the same time switches the conductor 451 from battery into connection with the winding of relay 7154. Conductor an is a common conductor which supplies buttery to the line relays, such as line relay 251, of all the rotary line switches such as the rotary line switch C, which are associated with this particular operators position. Suppose now that a call is received over the trunk line terminating in the cord circuit 0. lVhen relay 202 at the cord circuit is energized and closes the circuit of line relay 251, the said line relay is not now operated, due to the fact that the circuit now includes the winding of the high resistance relay 454. Relay 454; is energized, however, and connects the busy signallii'ig machine (a) with the common conductor 452 which extends to all the rotary line switches as shown in the case of the line switch C. The circuit from the busy signalling ma chine may now be traced by way of the common conductor 452, resting contact of armature 253 and the said HITHIMJHI'G, conductor 248, armature 217 and its working contact, armature 213 and its resting contact, and the condenser to the trunk couductor 130. It follows that the calliiiig subscriber willbe given a busy signal, which indicates to him that for the time being the desired connection cannot be obtained and he will replace his receiver.

Having described our invention, what we consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

hat we claim as our invention is:

1. In a telephone system, a manual exchange, trunk lines terminating in cord circuits in said exchange, automatic substations having access to said trunk lines for calling the subscribers in the manual exchange, a plurality of register sets for registering the telephone numbers of called manual stations, and an automatic progressively movable switch individual to each of said cord circuits for connecting its associated cord circuit with an idle register set when the cord circuit is taken for use.

2. In a telephone system, a manual exchange and an automatic exchange, interoflice trunk lines terminating in plug end ing cord circuits in the manual exchange, ofiice selectors in the automatic exchange having access to said trunk lines and operable by calling subscribers responsive to the first digits in called numbers, a plurality of sets of register switches associated with said cord circuits for registering the remaining digits in called numbers, an automatic switch individual to each of said cord circuits for connecting with an idle register set whenever a connection is extended to the associated cord circuit, an indicating device comprising a plurality of lamps. and means for operatively connecting operated register sets with said indicating device one at a time.

3. In a telephone system, a manual exchange, trunk lines terminating in cord circuits in said exchange, manual subscribers lines accessible to said cord circuits, automatic subscribers stations having access to said trunk lines for calling the said ,manual. lines, a plurality of register sets for registering the telephone numbers of manual lines so called, and an automatic progressively movable hunting switch individual to each of said cord circuits for connecting its as sociated cord circuit with an idle register set when the cord circuit is taken for use.

4. In a telephone system, a manual exchange, trunk lines terminating in cord circuits in said exchange, manualsubscribers lines accessible to said cord circuits, automatic subscribers stations having access to said trunk lines for calling the said manual lines, a plurality of register sets for registering the telephone numbers of manual lines so called, an automatic switch individual to each of said cordcircuits for connecting its associated cord circuit with an idle register set when the cord crcuit is taken for use, a set of indicating lamps common to said register sets, and means for switchingregistered calls on to said lamps one at a time.

5. In a telephone system, a manual exchange and an automatic exchange, a trunk line accessible to automatic switches in the automatic exchange and terminating in a cord circuit in the manual exchange, a series of step by step register switches for registering the numbers of manual lines called over said trunk lines, a switch individual to said cord circuit for-extending a connection to the first of said register switches when a line is being called, and a relay in said cord circuit for successively controlling all of said registers.

relay in said cord circuit for successively operating said magnets over a conductor passing through said individual switch.

7. In a telephone system, a plurality of register sets accessible to calling automatic stations for registering called telephone numbers, a common set oi indicating lamps tor indicating numbers so registered to an operator, means for causing numbers registered at the same time to be indicated by said lamps successively in a definite order of preference, and operator controlled means whereby a call registered on any register set may be given preference over all other calls.

8. In a telephone system, a plurality of register sets accessible to calling automatic stations for registering called telephone numbers, a common set of indicating lamps for indicating numbers so registered to an operator, means for causing numbers registered at the same time to be indicated by said lamps successively, in a definite order, and a key individual to each register set for causing a call registered thereon to be indicated by said lamps out of its regular turn.

9. In a telephone system, a plurality of register sets accessible to calling automatic stations for registering called telephone numbers, a common set of indicating lamps for indicating numbers so registered to an operator, means for causing numbers registered at the same time to be indicated by said lamps successively in a definite order of preference, and a key individual to each register set for placing such set first in order.

10. In a telephone system, a plurality of lines the numbers of which include a variable number of digits, a register set comprising sutlicient registers to register the number of a called one of said lines contain- 1ng the maximum number of digits, a device tor indicating any registered number to an operator, a timing mechanism set in motion when a number is registered which contains less than the maximum number of digits, and means controlled by said time mechanism for causing such number to be indicated after a definite time interval.

11. In a telephone system, a plurality of lines having numbers containing a variable number oi? digits, a set of serially related register switches for registering the digits in the numbers of said lines when called, a bank of indicating lamps, switching means for causing registered numbers to be indicated by said lamps to an operator, a relay in the final register switch for controlling said switching means, and means for controlling said switching means independent of said relay.

12. In a telephone system, a plurality of lines having numbers containing a variable number of digits, a setof serially related register switches for registering the digits in the numbers of said lines when called, a bank of indicating lamps, switching means for causing registered numbers to be indicated by said lamps to an operator, and a plurality oi devices for operating said switching means, the device used in any case depending on the number of digits in the called number.

18. In a telephone system, a plurality oi lines having numbers containing a variable number of digits, a set of serially related register switches for registering the digits in the numbers of said lines when called, a bank of indicating lamps, switching means for causing registered numbers to be indicated by said lamps to an operator, a time mechanism for operating said switching means after a definite time interval, and means for setting said mechanism in motion upon the operation of an intermediate register switch.

14. In a telephone system, a plurality of lines having telephone numbers containing a variable number of digits, a register set for registering the numbers or said lines when called, said set comprising sutlicient register switches to register numbers having the maximum number of digits, a device for indicating any registered number to an operator, a timing mechanism set in motion while a number is being registered, and means controlled either by said time mechanism or by the last register switch for causing the registered number to be indicated on said device.

15. In a telephone system, a plurality of lines having telephone numbers containing a variable number of digits, a register set for registering the numbers of said lines when called, said set comprising suilicient register switches to register numbers having the maxii'num number of digits, a device for indicating any registered number to an op erator, a timing mechanism for causing registered numbers to be indicated on said device after a definite time interval, means for setting said mechanism in motion upon the operation of an intermediate register switch, means for stopping the operation of said mechanism when the final register switch is operated in case the called number contains the maximum number of digits, and means for causing the registered number to be indicated on said device after the last register switch has finished operating.

16. In a telephone system, private lines and party lines terminating in a manual eX- change, the stations on said lines being numbered in accordance with a system in which the number of each party line station contains an extra digit, trunk lines extending to said exchange and accessible to automatic subscribers for calling said private and party lines, a register set for registering the digits in the numbers of lines so called, said set comprising as many T, itQFS as there are digit s in a party line number, an indicating device :tor indicating numbers so regis tered to. an operator, a timing mechz'inism set in motion when the final digit in a private line number is registered, and switching means for causing registered numbers to be indicated on said device, said switching means being operable by said time mechanism after a definite time interval and being also operable by the final register switch in case such switch is operated before the time interval. has expired.

17. In a telephone system, an automatic exchange and a manual exchange, serially related switching devices in both exchanges which are controlled by a calling automaticsubscriber in accordance with thedigits in called automatic and manual telephone numbers, respectfully, means in the last switching device in the series in the automatic exchange for completing the connection to a called automatic line, number indicating means controlled by the switching devices in the manual exchange, operators equipment for completing the connection to a called manual line, means for automatically signalling the called subscriber in both cases, and means for giving the calling sub scriber auniform audible signal during the ringing operation in both cases.

18. In a telephone system, a manual exchange, trunk lines terminating in cord circuits in said exchange, manual subscribers linesaccessible to said cord circuits, automatic subscribers stations having access to said trunk lines for calling the said manual lines, a plurality of register sets for registering the telephone numbers of manual lines so called, an automatic switch for each of said cord circuits for connecting its associa-ted cord circuit with an idle register set when the cord circuit is taken for use, and means for giving the calling automatic subscriber a busy signal in case all of said register sets are busy.

19. In a telephone system, amanual exchange, trunk lines terminating in cord circuits in said exchange, automatic substalions having access to said trunk lines for calling the subscribers in the manual 6X- change, a plurality of register sets for registering the telephone numbers oi. called manual stations, and a step by step automatic switch for. each of said cord circuits for selecting an idle register set and for com nectingits associated cord circuit therewith when the cord is taken for use.

20. In a telephone system, a plurality of lines having numbers containing a veriable number of digits, a set of serially related register switches for registering the digits in the numbers of said lines when called, a

bank of indicating lamps, switching means for causing registered numbers to be indicated by said lamps to an operator, and a relay in the final register switch for initiating the operation of said switching means.

21. In a telephone system, a manual exchange, trunk lines terminating in cord circuits in said exchange, manual subscribers lines accessible to said cord circuits, aut0- matic subscribers stations having access to said trunk lines for calling the said manual lines, a plurality of register sets common to said cord circuits for registering the telephone numbers of manual lines so called, and a non-restoring automatic. switch individual to each of said cord circuits for connecting its associated cord circuit with an idle register set when the cord circuit is taken for use.

22. In a telephone system, a manual exchange and an automatic exchange, a trunk line accessible to automatic switches in the automatic exchange and terminating in a cord circuit in the manual exchange, a series of register switches for registering the numbers of manual lines called over said trunk lines, a switch individual to said cord circuit for extending a connection to the first of said register switches when a line is being called, a relay in said cord circuit controlled over said trunk line by decimal impulses corresponding to the digits in the called number, an operating magnet in the first register switch controlled by said relay responsive to the first digit, and operating magnets in the other register switches successively controlled thereafter by said relay responsive to the remaining digits.

23. In a telephone system, a manual exchange, trunk lines terminating in said exchange, cord circuits for connecting said trunk lines with manual lines, automatic subscribers stations having access to said trunk lines for calling the said manual lines, a plurality of register sets in the manual exchange :tor registering the telephone numbers of manual lines so called, automatic switching mechanism for connecting a trunk line with an idle register set when the trunk line is taken for use, and means for giving the calling subscriber a busy signal in case all said register sets are busy.

Signed by us at Chicago, Cook County, Illinois, this 9th day of March, 1920.

TALBOT G. MARTIN. BERNARD D. WILLIS. 

